The present invention relates to treatment of biological organisms which includes selective removal of tissue mass therefrom by use of vibrational forces, such as ultrasonic vibrational forces, and in particular, to an apparatus and method for reducing and removing tissue mass from the organism using a treatment fluid.
The principles of the present invention are broadly applicable to the removal of layers of tissue mass, and are particularly adapted for use in conjunction with removal of organic tissue such as that found in the eye.
It has been known in the art of removing unwanted tissue mass from animals, such as humans, to effect such removal by use of ultrasonic energy. Specifically, in the art relating to removal of cataracts, it is known to use a tip in the form of a hollow needle which is subjected to ultrasonic vibration, and is surrounded by a plastic tube which is not subjected to vibration. This combined tube and needle can be inserted into the anterior chamber of the eye through a small incision, while provision is made for maintaining hydrodynamic flow both in the area between the needle and the tube and within the interior of the vibrating tube. It is of the greatest importance in prior art procedures that a proper balance be established between the two flows in order to prevent an excessive build up of pressure in the anterior chamber or a reduction in pressure which could cause a collapse of the anterior chamber.
In order to insure maintenance of this sensitive and delicate balance, practitioners have found it necessary to use a very complex electro-hydraulic means having a series of failsafe characteristics incorporated therein. Moreover, problems can be encountered in insuring that every particle of dispersed cataract material is aspirated before making some unwanted orbit in the anterior chamber. In other words, for example, if a population of 100,000 small particles were created by ultrasonic microchopping, these particles are created in the presence of an inflowing stream of liquid combined with an adjacent rapidly outflowing stream of liquid. The hydrodynamic circulation in the anterior chamber, or in the posterior chamber if that is the area of operation, under these circumstances would allow for the movement in the anterior chamber of those few particles which might accidently escape from time to time during the operation.
In the case of hard cataracts such particles could very well have an abrasive character if they were to slide past in contact with the walls of the chamber. In the case of the endothelium of the cornea which forms a part of this chamber, there is extreme sensitivity to any such abrasion and must be avoided at all costs.
Briefly, the procedure known today, such as disclosed in U.S. Pat. No. 3,589,363, includes a process for removal of cataracts by emulsifying the the lens with an ultrasonic probe requiring aspiration of the emulsified material. Since aspiration is a required aspect of the procedure, it is necessary to have complex electronic and hydraulic equipment for delicate control of inflow and outflow in the eye. This complex equipment requires a trained technician to control and monitor such equipment, especially since the aspiration requires very careful manipulation of the tip by the surgeon in order to prevent aspirating other than cataract material.
Other disclosures such as U.S. Pat. No. 3,990,452, U.S. Pat. No. 3,776,238, and U.S. Pat. No. 4,099,529, describe instruments for ophthalmic surgery which consists of a hollow needle with internal moveable hollow cylinder, capable of cutting tissue by reciprocation, and in which an opening has been formed in the outer needle so that material can be engaged by the inner plunger so as to be sheared. See also U.S. Pat. No. 4,428,748 which discloses combined ultrasonic emulsifier and mechanical cutter for surgery including an outer tube means and an inner tube means mounted by reciprocal driving in order to shear eye tissue.
Another method of removing cataract material from the eye is disclosed in a series of patents which describe ultrasonic instrumentation and a method for removal of unwanted tissue material from an animal by use of cryogenic application and ultrasonic vibration in combination with a flow of liquid and cataract mass from an incision in the eye structure. See U.S. Pat. Nos. 3,857,387; 3,942,519; 3,952,732 to Shock. This method, however, suffers from certain procedural and instrumentative drawbacks, such as indiscriminate and uncontrolled emission of fluid from the eye structure. This condition detracts from surgical procedure in that it provides a continuous flow of fluid which creates a sloppy surgical work area, and does not insure complete reduced-mass removal.
It is, therefore, an object of the present invention to provide an improved apparatus and method for removing a mass of tissue from an animal, such as a human.
Another object of the invention is to provide an improve apparatus and method for removing cataracts.
A further object of the present invention is to provide an apparatus and method for selectively micro-chopping and removing layers of living organic tissue from a biological organism.
Another object of the invention is to provide an apparatus and method for the removal of living organic tissue from a cataract in a rapid manner and with little or no mess created by use of treatment fluids. A further object of the invention is to provide a hydrodynamically balanced fluid flow to the treatment area. Other objects and advantages of the present invention will become apparent as the disclosure proceeds.